The floating potential of a rocket and the return current distribution were measured simultaneously in the S-520-2 electron beam experiment in the ionosphere. When an electron beam is emitted perpendicular to the geomagnetic field, it returns back to the rocket surface azimuthally opposite (180¿) to the electron gun and this results in a suppression of the floating potential. An apparent spurious increase of the floating potential of the rocket when the electron beam directly hits the floating probes causing the charge-up of those probes is also pointed out.